Baits that I made with MF plastic would usually have oil in the bottom of the bag, even if I didn't add scent. They just seemed to leach out some oil as time passed. Maybe Zoom uses MF? Bait plastics and dead-on plastics stay dry and will absorb added scent. As long as you use a strong scent and put it in a laminated worm bag with a zipper, it will hold its scent after it looks like it has dried out. I've used clear bags for a long time but recently switched to a black and silver bag from wormbags.com. They all work well.